Thread: Change capital letters to low case and the other way around in a text file - help

There is no rt specifier for fopen as long as i know.

Also think what this line of code gives you access to

Code:

*texto

and what this line of code gives you access to

Code:

*texto[i]

I think you need the second.

Here is a code i used some days ago for a binary copy file operation.I think it can motivate you a bit

Code:

/* File: filecopy.c */
#include <stdio.h>

int main(int argc, char *argv[])
{ FILE *ifp, *ofp;
  int n;
  char buf[1024];
  if (argc != 3) {
    fprintf(stderr,
            "Usage: %s <soure-file> <target-file>\n", argv[0]);
    return 1;
  }
  if ((ifp = fopen(argv[1], "rb")) == NULL) { /* Open source file */
    perror("fopen source-file");
    return 1;
  }
  if ((ofp = fopen(argv[2], "wb")) == NULL) { /* Open target file */
    perror("fopen target-file");
    return 1;
  }
  while (!feof(ifp)) {  /* While we don't reach the end of source */
               /* Read characters from source file to fill buffer */
    n = fread(buf, sizeof(char), sizeof(buf), ifp);
                          /* Write characters read to target file */
    fwrite(buf, sizeof(char), n, ofp);
  }
  fclose(ifp);
  fclose(ofp);
  return 0;
}

I'm afraid that doesn't motivate me much.. Is using the malloc function to create another string with the size needed to have all the lines and letters and then copying the texto string to that one the way to go? I'm pretty much lost here.

There isn't really any point in reading an entire line into an array when you can just process the file character by character. Also, for the sake of writing portable code, it's better to use the ctype functions instead of your character set's values. Copying a file with each character's case changed shouldn't be much more difficult than the following:

Code:

#include <ctype.h>
#include <stdio.h>

int main(void)
{
    int c;

    while ((c = getchar()) != EOF)
        putchar(islower(c) ? toupper(c) : tolower(c));
    return 0;
}